72 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
TABLE 5. Candidate models used to model Sedge Wren occurrence. Plantl-Plant5 are principal components of the 
plant species guilds. Herb = herbaceous structure. Wood = woody understory structure, and Tree = tree density. 
Model 
AICc AAICc 
' 1 GIC 
Wood PC + Basal area 
Basal area 
Wood PC + Canopy closure 
Herb PC + Tree PC 
Canopy closure 
Wood PC + Herb PC + Tree PC 
Wood PC 
Null 
Plant5 
Herb PC + Plant4 
Plant2 
Wood PC + Herb PC 
Herb PC 
Plant 1 
Wood PC + Plant4 + Wood PC*Plant4 
Plant 1 + Plant5 
Plant2 + Plant4 
Plant 1 + Plant4 
Plant 1 + Plant2 
Plant 1 + Plant2 + Plant4 + Plant5 
Global 
28.08 
0.00 
0.07 
0.17 
30.49 
2.41 
0.06 
0.09 
30.59 
2.52 
0.06 
0.09 
30.93 
2.86 
0.06 
0.08 
31.00 
2.93 
0.06 
0.07 
31.24 
3.17 
0.06 
0.07 
32.73 
4.65 
0.05 
0.01 
33.06 
4.99 
0.05 
0.00 
33.56 
5.48 
0.05 
-0.02 
34.59 
6.51 
0.05 
-0.06 
35.10 
7.03 
0.05 
-0.08 
35.16 
7.09 
0.05 
-0.08 
35.30 
7.22 
0.05 
-0.09 
35.39 
7.31 
0.05 
-0.09 
35.95 
7.87 
0.04 
-0.11 
36.09 
8.01 
0.04 
-0.12 
36.77 
8.69 
0.04 
-0.15 
37.04 
8.97 
0.04 
-0.16 
37.63 
9.55 
0.04 
-0.18 
40.69 
12.61 
0.04 
-0.33 
46.86 
18.78 
0.03 
-0.67 
too patchy to provide suitable habitat. The; 
results demonstrate that fire history alone may n 
predict sparrow occurrence in pine savanna 
Henslow’s Sparrows will use both upland longle, 
pine savannas and bogs in some areas, bi 
apparently prefer bogs when surrounding uplar 
habitat is of marginal quality, as is the case i 
DSNF. Small-scale bog restoration may fc 
important for Henslow's Sparrows in these area 
Henslow s Sparrow stand occurrence in DSN 
was best predicted by increasing continuou: 
spatially homogenous herbaceous density, whic 
is also reflected by their avoidance of uplan 
stands Qur results support those of Rotenberr 
and Wiens (1980) who found abundance o 
tallgrass praine birds, including breeding Hen 
Slow s Sparrows, was negatively correlated will 
ground cover heterogeneity. Patchy herbaceou 
structure can have negative effects on grasslan, 
buds in multiple ways (Shriver 1996, Perkins an. 
Vickery 2001, Thatcher et al. 2006) 
Cover of the sedge Scleria muhlenbergi 
increased the probability of Henslow’s Sparrov 
stand occurrence. This sedge can reach > 50 <2 
cover in some bogs in DSNF but does not occur ir 
upland stands. All bogs that had high densities 01 
Henslow s Spmrows also had high cover of 5 
muhlenbergu. Scleria is an annual that senesces 
achenes in autumn (W. J. Platt, pers. comm.), and 
the seeds are available to ground-foraging birds in 
early winter. Species of Scleria have been found 
to be important in Henslow’s Sparrow diets in 
Mississippi and Louisiana (Fuller 2004, DiMiceli 
2006). Schleria muhlenbergii could be important 
for identifying high-quality habitat if Henslow’s 
Sparrows use habitat cues to select wintering 
areas upon fall arrival. Scleria muhlenbergu 
responds strongly to fire and is most abundant 
the first growing season after fire, but decreases 
substantially by the following season in the 
absence of fire (W. J. Platt, pers. comm.). 
Henslow’s Sparrow use of RCW stands was 
ephemeral. Mean Henslow’s Sparrow density in 
RCW stands declined from 3.5 birds/ha in late 
November to 0.6 in early January (Brooks 2010). 
Henslow’s Sparrows are site faithful during the 
core months of winter (Dec-Feb) (Plentovich et 
ah 1998a, Thatcher et al. 2006, Johnson et al. 
009 ). Oui results suggest temporary use of RCW 
stands by transient birds that had not settled on 
winter territories, a result that corresponds to 
movements described in Louisiana (Johnson et al. 
2009). RCW stands in DSNF had lower herba¬ 
ceous structure than bog stands, indicating the 
habitat was of lower quality than bogs, where 
densities did not significantly decline during the 
